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Metamath Proof Explorer

Theorem nnon

Description: A natural number is an ordinal number. (Contributed by NM, 27-Jun-1994)

		Ref	Expression
	Assertion	nnon	$⊢ A \in ω \to A \in On$

Step	Hyp	Ref	Expression
1		omsson	$⊢ ω \subseteq On$
2	1	sseli	$⊢ A \in ω \to A \in On$